Host selectivity behaviour of trans-N,N′-bis(9-phenyl-9-xanthenyl)cyclohexane-1,2-diamine and trans-N,N′-bis(9-phenyl-9-thioxanthenyl)cyclohexane-1,2-diamine when presented with six-membered heterocyclic guest mixtures

Two compounds, trans-N,N′-bis(9-phenyl-9-xanthenyl)cyclohexane-1,2-diamine (1,2-DAX) and trans-N,N′-bis(9-phenyl-9-thioxanthenyl)cyclohexane-1,2-diamine (1,2-DAT), were assessed for their host ability in the presence of four heterocyclic guest species, namely pyridine (PYR), piperidine (PIP), morpholine (MOR) and dioxane (DIO). Each of these guests formed single solvent complexes with both host compounds. When 1,2-DAX and 1,2-DAT were recrystallized from various guest mixtures, it was shown that their selectivity orders were identical, DIO (46.6%) > MOR (23.0%) > PYR (18.9%) > PIP (11.5%) and DIO (85.9%) > MOR (23.7%) > PYR (8.9%) > PIP (8.5%), respectively, but that the thio host derivative possessed a significantly enhanced preference for DIO compared with its oxygen analogue. Additional experiments in order to investigate the various parameters at play in these complexation experiments involved single crystal diffraction experiments and thermal analyses.